refine for go doc

Author: JacksonTian

.gitignore

@@ -1 +1,2 @@
 coverage.txt
+coverage/

README.md

@@ -1,7 +1,8 @@
 # Debug for Golang
 
-- [![Go CI](https://github.com/alibabacloud-go/debug/actions/workflows/go.yml/badge.svg)](https://github.com/alibabacloud-go/debug/actions/workflows/go.yml)
-- [![codecov](https://codecov.io/gh/alibabacloud-go/debug/branch/master/graph/badge.svg)](https://codecov.io/gh/alibabacloud-go/debug)
+[![Go CI](https://github.com/alibabacloud-go/debug/actions/workflows/go.yml/badge.svg)](https://github.com/alibabacloud-go/debug/actions/workflows/go.yml)
+[![codecov](https://codecov.io/gh/alibabacloud-go/debug/branch/master/graph/badge.svg)](https://codecov.io/gh/alibabacloud-go/debug)
+[![Go Reference](https://pkg.go.dev/badge/github.com/alibabacloud-go/debug.svg)](https://pkg.go.dev/github.com/alibabacloud-go/debug)
 
 ## Usage
 

debug/assert.go

@@ -1,3 +1,22 @@
+// Package debug is a library to display debug info that control by enviroment variable DEBUG
+//
+// # Example
+//
+//	package main
+//	// import the package
+//	import "github.com/alibabacloud-go/debug/debug"
+//
+//	// init a debug method
+//	var d = debug.Init("sdk")
+//
+//	func main() {
+//		// try `go run demo.go`
+//		// and `DEBUG=sdk go run demo.go`
+//		d("this debug information just print when DEBUG environment variable was set")
+//	}
+//
+// When you run application with `DEBUG=sdk go run main.go`, it will display logs. Otherwise
+// it do nothing
 package debug
 
 import (
@@ -6,6 +25,8 @@ import (
 	"strings"
 )
 
+// Debug is a method that display logs, it is useful for developer to trace program running
+// details when troubleshooting
 type Debug func(format string, v ...interface{})
 
 var hookGetEnv = func() string {
@@ -16,6 +37,7 @@ var hookPrint = func(input string) {
 	fmt.Println(input)
 }
 
+// Init returns a debug method that based the enviroment variable DEBUG value
 func Init(flag string) Debug {
 	enable := false
 

debug/debug.go

@@ -26,7 +26,9 @@ func TestMain_Matched(t *testing.T) {
 	}
 	debug := Init("sdk")
 	debug("%s", "testing")
-	assertEqual(t, "testing", output)
+	if output != "testing" {
+		t.Errorf("%v != %v", output, "testing")
+	}
 }
 
 func TestMain_UnMatched(t *testing.T) {
@@ -46,5 +48,7 @@ func TestMain_UnMatched(t *testing.T) {
 	}
 	debug := Init("sdk")
 	debug("%s", "testing")
-	assertEqual(t, "", output)
+	if output != "" {
+		t.Errorf("output failed")
+	}
 }